1. Field of the Invention
The present invention relates to an air conditioner, and more particularly, to the structure of a wind-directing-plate driving means attached in a large ceiling-mounted type of an indoor unit which is installed, for example, on the ceiling of a room, and to a wind directing plate which is preferable for a large indoor unit.
2. Description of the Related Art
Air conditioners are broadly divided into three types, that is, wall-mounted, floorstanding, and ceiling-mounted types, according to the ways they are mounted. Of these three types, the ceiling-mounted type of an air conditioner is mainly used in a larger space such as an office, and a store, to be placed on the ceiling. This type of an air conditioner is larger than, for example, a wall-mounted, or floorstanding type in structure, but has an advantage of effectively utilizing the space of a wall and a floor of a room.
Usually, a wind vertically directing plate (hereinafter, referred to as a flap) vertically rotatable around a horizontal axis of rotation, and a wind laterally directing plate (hereinafter, referred to as a louver) laterally rotatable around an axis of rotation almost perpendicular to the horizontal axis of rotation are disposed in an air outlet of an air conditioner. In the case of a ceiling-mounted type of a larger unit, its flap is , for example, 1500 mm in length, and 90 mm in width.
A flap and a louver are respectively driven by different motors, and the ways to drive them are broadly divided into two ways described below. One of them is to use a synchronous motor. With a synchronous motor, greater torque is obtained at a low cost, but there is a disadvantage of requiring a complicated link mechanism and a limit switch in order to control the position where its rotation stops and its rotational direction.
The other way is to use a stepping motor. A stepping motor with a gear reducer being incorporated therein is used for driving a wind directing plate, and usually its reduction gear ratio is about 1/40. A stepping motor allows complicated rotation control or the like without requiring a link mechanism or a limit switch.
However, a stepping motor has small output torque even with the aforementioned reduction gear ratio, therefore it has a disadvantage of insufficient torque for enduring external force when stopped without electric current, that is, insufficient detent torque, when the stepping motor is used for a large-sized flap applied especially to a ceiling-mounted type.
In order to compensate the aforementioned disadvantage, it is necessary to additionally carry out gear reduction outside. FIG. 17 shows the conventional example of the case in which gear reduction is additionally conducted outside. Based on this drawing, the configuration of a flap driving means will be explained. It should be mentioned that FIG. 17 is a cross-sectional view when a side plate portion of an air outlet is seen from the top of a housing.
According to the drawing, a flap driving means 1 is attached on a side plate 3 forming a part of an air outlet 2, and by this flap driving means 1, a flap 4 in the air outlet 2 is vertically driven rotatively around a horizontal axis of rotation X. Incidentally, the entire body of the flap driving means 1 is covered with a side cover 5 of the housing.
The flap driving means 1 includes a motor base 6 attached on the side plate 3. The motor base 6 has a first supporting base plate 6a in a size blocking an opening, which is for attaching the motor base, and which is formed on the side plate 3, a second supporting base plate 6b made almost vertical from the first supporting base plate 6a towards the outside surface of the side plate 3, specifically, the side cover 5 side, up to a predetermined height, and a third support base plate 6C bent to be parallel to the aforementioned first supporting base plate 6a from the upper end of the second supporting base plate 6b, all of which are made of synthetic resin.
The second supporting base plate 6b has a motor attaching frame 7 formed to be parallel to the aforementioned first supporting base plate 6a, and a stepping motor 8 having a gear reducer incorporated therein is secured to the frame 7 with screws with a driving shaft 8a thereof facing the third supporting base plate 6c side. A pinion gear 8b is secured to the driving shaft 8a with screws, and the third supporting base plate 6c is provided with a bush 9a serving as a bearing for the pinion gear 8b.
An output gear 10 meshed with the pinion gear 8b is provided between the first supporting base plate 6a and the third supporting base plate 6c of the motor base 6. An output shaft 10a is secured to the output gear 10 with screws. The output shaft 10a is located on the horizontal axis of rotation X of the flap 4, extending through the first supporting base plate 6a into the air outlet 2, and is coupled with the flap 4.
In this case, in order to keep the axis of the output gear 10 parallel to the axis of the pinion gear 8b, the third supporting base plate 6c is provided with a bearing bush 9b, and the first supporting base plate 6a is coaxially provided with a bearing hole 11 for the output shaft 10a. Incidentally, an E-ring (retaining ring) 12 is fitted onto the output shaft 10a at the position close to the bearing hole 11 in order to prevent rattling in the axial direction.
According to the flap driving means 1, the output from the stepping motor 8 is further reduced by the output gear 10, and is transmitted to the flap 4, thereby obtaining predetermined detent torque. However there are disadvantages described below.
First of all, due to a large number of components required, there is a disadvantage in assembling operability. Specifically, in the prior art, when coupling the pinion gear 8b to the driving shaft 8a of the stepping motor 8, and when coupling the output shaft 10a to the output gear 10, they are fastened with screws. Further, the third supporting base plate 6c of the motor base 6 needs to be provided with two of the bearing bushes 9a and 9b for the pinion gear 8b and the output gear 10.
Next, since the stepping motor 8 is held in the motor base 6, the motor base 6 itself needs to have a large size. Therefore, the flap driving means 1 becomes larger in size, and a larger space for attaching the same must be secured.
Further, the backlash of the inner gear of the stepping motor 8, the pinion gear 8b, and the output gear 10 appears as rattling of the flap 4. Especially when the flap 4 is rotated and its center of gravity is located above the horizontal axis of rotation X, the center of gravity is deviated according to the angle of the flap 4, therefore it seems that rattling occurs to the flap 4.
Meanwhile, in a larger unit like a ceiling-mounted type, its flap 4 needs to have for example, a length of 1500 mm and a width of 90 mm as described in the above. However, in order to obtain such a flap 4 by molding resin, slimmer molding die must be used, therefore it is difficult to secure the rigidity of the die. Accordingly, a larger-sized molding die compared to the molded flap 4 is used, therefore a large-sized injection machine must be used.
A slim cavity in a molding die doesn't allow smooth flow of resin material, thereby easily causing warp, sink, flow mark, weld, or the like. The aforementioned disadvantage is eliminated when using the flap 4 made of metal plate, but moisture condensation easily occurs to the flap 4 due to high thermal conductivity of the metal plate. Therefore, piled cloth or the like is set thereon, but in addition to high cost required, it is difficult to clean it when dust or the like is settled thereon. Further, metal plate is not preferable, since it is heavier than resin and gives an additional load to the motor.